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NanoTag® selector resins are based on a high-affinity single-domain antibody (sdAb) that is covalently immobilized on 4 % cross-linked agarose beads. The innovative, oriented and selective attachment via a flexible linker guarantees a high accessibility of the sdAbs and largely eliminates batch-to-batch variations. Due to the single-chain nature of sdAbs and their stable and covalent attachment, no leakage of light and heavy chains is observed during elution with SDS sample buffer. Selector resins thus features high affinity and superior capacity, while showing negligible unspecific background. Selector resins are compatible not only with physiological buffers but also with high stringency buffers. Selector resins thus provide great freedom to adjust the binding and washing conditions to the experimental needs.
The ALFA-tag is a novel, rationally designed epitope tag (SRLEEELRRRLTE) that forms a small and stable α-helix that is functional irrespective of its position on the target protein in prokaryotic and eukaryotic hosts.
For a poster with detailed information on the ALFA System and its applications click here
The flanking proline residues are not part of the recognition sequence, but may aid in spacial separation of the tag from the protein of interest.
For immunoprecipitations we offer two types of ALFA Selector resins. Both ALFA Selectors are based on covalently coupled nanobodies that specifically recognize ALFA-tagged targets. ALFA Selector ST (for Super-Tight) offers the highest possible affinity for ALFA-tagged targets, which can be eluted under acidic or denaturing conditions. ALFA Selector PE (for Peptide Elution) displays an engineered nanobody with lower affinity (Kd ~11 nM), which is optimized for peptide elution under physiological conditions. Both Selector resins feature low non-specific protein adsorption and therefore allowing clean and meaningful immunoprecipitations. Due to the covalent and oriented immobilization, the immobilized nanobodies will stay on the resin even when using harsh denaturing and/or reducing conditions for elution. In contrast to conventional immunoprecipitations, eluates from both ALFA Selectors will therefore be free from large amounts of antibody fragments.